-LRB- CNN -RRB- -- Even though he sailed to the White House on the wings of his soaring rhetoric , President Barack Obama could find that he is on mission impossible as he launches his media blitz on Syria this week -- six television interviews on Monday and a dramatic prime time address on Tuesday . Perhaps he will persuade a skeptical public , but it is surely the toughest speaking assignment of his presidency .

Surprisingly , he is now tripling down on his Syrian bet .

First he drew the red line , uncertain whether President Bashar al-Assad would call his bluff . Then he doubled down by insisting on a vote from an unreliable Congress . Now he is placing almost all his chips on the table by betting on his capacity to turn around public opinion .

If he wins over the public , he will likely win Congress , too , but if he fails , he will have turned a problem in Syria into a crisis in his presidency . -LRB- Someday , in their memoirs , will White House insiders please tell us what they were thinking ? -RRB-

There are at least two major hurdles in his path as he seeks to persuade the public . First , he will be trying to change opinion that has already started to harden against him . Second , the bully pulpit may not be as powerful as often imagined .

The intensity factor

It 's hard to remember a public terrain as rough as this one for a president in the past few decades . Weary of war and wary of another , Americans are in no mood to rally behind this call to arms -- many do n't see it as our fight , they worry that it will drag us in deeper and even some of his most ardent supporters think the president and his team do n't have a firm grip on the wheel .

A Gallup poll late this past week found that a majority of the public -LRB- 51 % to 36 % -RRB- is opposed to a Syrian strike . That is the lowest level of support Gallup has found for any intervention in two decades . Moreover , the `` intensity factor '' runs much more strongly among opponents -- just look at the avalanche of their calls and e-mails to Capitol Hill .

The president has been arguing his case for nearly three weeks , and so far , he does n't have many converts on the Hill . That 's among Democrats as well as Republicans . CNN 's whip count suggests that he could win a tight vote in the Senate -LRB- his speech may work best there -RRB- , but a strike resolution is in serious trouble in the House . The Washington Post count shows that as many as a third of House Democrats may vote no .

Even overseas , among nations much closer to Syria , the president 's rhetorical offensive has fallen short . No president in modern times has had such a tiny coalition behind him . Eighteen nations contributed to the intervention in Libya . President George W. Bush had 48 nations in the coalition that attacked Saddam Hussein . This time around , Obama will have only a handful supporting his intervention and most will be cheering from the sidelines .

A shaky pulpit

This controversy is also coming at an inopportune moment for the president . Early on at the White House , he could command massive , almost adoring audiences at every major address . But with the exception of his speech announcing the killing of Osama bin Laden , the numbers tuning in have dropped , viewers tend to be more partisan and television commentators have toughened up on him . Notably , his two Syrian interviews on television so far have drawn only modest audiences .

It has been little noticed but is important now that Obama has also had more success selling himself than his policies .

Obama 's speeches -- despite their rhetorical strength and skilled delivery -- have had little success in moving his agenda forward . Americans still like him , but they tend to make up their own minds about his policies . Witness his inability , even now , to build a public majority in favor of Obamacare . The White House would argue that a majority have supported his stands on gun control and gay rights , but is that because of his speeches or because of demographic shifts and events such as the Newtown elementary school massacre ?

Indeed , there is now a debate among political scientists whether the bully pulpit is all that it is cracked up to be , especially in contemporary politics .

Professor George Edwards of Texas A&M University and a dean among political scientists concluded in his 2006 book , `` On Deaf Ears : The Limits of the Bully Pulpit , '' that we have a highly inflated view of how much presidents have been able to change public minds through their speeches .

He presents numerous cases to support his argument and one that is especially relevant today :

President Franklin D. Roosevelt had a legendary ability to connect with Americans through his fireside chats , but when it came to convincing a skeptical public about his Supreme Court-packing bill in his second term , the fire fizzled out . Edwards ' data also suggests that presidents only succeed in mobilizing the public when opinion is already in their favor . This is clearly not the case with Syria .

To our memory , the last Oval Office address that dramatically moved the public opinion needle over military conflict came in late 1983 when President Ronald Reagan spoke to the country about a bloody attack on marine barracks in Lebanon and U.S. intervention in the tiny island of Grenada . Public support for military action jumped 10 points in immediate polling . But in that case , Reagan was telling a story about what had already happened to a public whose majority already favored intervention . He was not asking them to rally round a new , uncertain venture , and he was also still in his first term when audiences were big .

This is not to argue that all is lost for Obama on Tuesday night . Big speeches can reframe issues . They can unite us behind a higher purpose . They can push us to question our firmly held beliefs . Obama does have unusually persuasive powers . Perhaps he can come up with fresh arguments that will bring undecideds in his direction . Perhaps he will have horrific new evidence of how brutal al-Assad is .

Perhaps ... perhaps , but if he has new arrows in his quiver , he likely would have shot them by now .

The opinions expressed in this commentary are solely those of David Gergan and Dan Katz

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Gergen , Katz : Rarely has a president faced as tough a public mood as does Obama

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They say he has ability to get people to like him but may not be persuasive on Syria

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Authors : Public mood seems strongly against intervention

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Researchers say the impact of the White House `` bully pulpit '' has been exaggerated